Pat Finucane, Murdered in 1989
Tonight's BBC Panorama programme included a secretly taped interview with leading Loyalist, Ken Barrett, who described how he was allegedly encouraged by RUC elements to carry out the shooting of Mr Finucane in 1989.
Speaking at Stormont earlier, Mr McGuinness said the revelations about collusion and the murder of Belfast solicitor, Pat Finucane, in 1989 have the potential to be "absolutely massive".
He added that "the lid is now off the can of worms" surrounding British military intelligence activity in the North and that Tony Blair's worst fears are now being realised.
The Mid Ulster MP also said the details of the Panorama programme make a compelling case for the establishment of an international public inquiry.
Earlier. SDLP Policing Board member, Alex Attwood, said that people's worst fears regarding the activity of the British army and elements of the police would be confirmed by the programme.
The West Belfast MLA also said the case for a full public judicial inquiry into the Finucane murder was now compelling and essential if there was to be any confidence in the future of policing.
